In general, space frame construction refers to a type of structure wherein a number of lattice members converge and are fastened at a node. By geometrically locating nodes properly, long distances can be spanned with a lighter weight of material while achieving a strength not otherwise possible with such weight of material. In short, space frame construction is intended to provide light weight, high strength, easy to build, inexpensive structures. In many circumstances, space frame construction replaces more traditional structure, such as steel beams, stone or mortar spans, arches, and domes.
Space frame construction has been successful. It has not, however, realized early expectations with respect to being as light weight and as inexpensive as once hoped. Although lattice members are generally light weight and inexpensive, nodes and connections to them are not. A commonly used node is a steel ball machined to have a plurality of facets, usually eighteen, with each facet being tapped to receive a threaded shaft. A common lattice member has a threaded shaft fastened to an end. The lattice member is screwed or threaded into the facet receiving opening. Such node is not only heavy and expensive to make, but assembly of the lattice members to the node is time consuming and must be carefully planned.
Somewhat similarly, U.S. Pat. No. 4,355,918 shows a node formed from three stacked elements held together by a nut and bolt combination. Lattice members having headed ends are received in sockets formed by the elements and are held in place when the nut and bolt combination tightens the stacked elements of the node.
U.S. Pat. No. 4,562,682 shows a node formed from a cup reinforced with a concrete base. The cup supports bolts which are threaded into tapered, threaded ends of lattice members.
Over the years, it has become clear that if space frame construction is to achieve its early expected potential, nodes must be lighter and simpler, and the assembly of the space frame must be sufficiently easy to reduce assembly time relative to traditional span structures.